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| CMS-PAS-SMP-23-003 | ||
| Search for charged lepton flavor violating Z and Z' boson decays in proton-proton collisions at $ \sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| 13 March 2025 | ||
| Abstract: A search for charged lepton flavor violating decays of the Z boson is performed using data from proton-proton collisions at $ \sqrt{s}= $ 13 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb$ ^{-1} $. The Z $ \rightarrow $ e$ \mu $, Z $ \rightarrow $ e$ \tau $, and Z $ \rightarrow\mu\tau $ decays are considered separately, where hadronic and different-flavor leptonic $ \tau $ decays are used in the latter two searches. The data are found to be consistent with expectations from the standard model. For the Z $ \rightarrow $ e$ \mu $ channel the observed (expected) 95% CL upper limit on the branching fraction is 1.9 $ \times 10^{-7} $ ( 2.0 $ \times 10^{-7} $), which is the most stringent direct limit to date on this process. The corresponding limits for the Z $ \rightarrow $ e$ \tau $, and Z $ \rightarrow\mu\tau $ channels are 13.8 $ \times 10^{-6} $ ( 11.4 $ \times 10^{-6} $) and 12.0 $ \times 10^{-6} $ ( 5.3 $ \times 10^{-6} $), respectively. Additionally, the e$ \mu $ final state is used to search for lepton flavor violating decays of resonances in the mass range from 110 to 500 GeV. No significant excess is observed above the predicted background levels. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, Submitted to PRD. The superseded preliminary plots can be found here. |
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Compact Muon Solenoid LHC, CERN |
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